NULL values not handled in pub/sub message

[manikyafc]

Client tracking pushes null invalidate upon flush which is not handled by node-redis (more info on redis/redis#7463).

FILE: commands-queue.js,
FUNCTION: _RedisCommandsQueue_emitPubSubMessage
ISSUE: does not handle the case when message is null (for eg- redis/redis#7463)

Environment:

• Node.js Version: v12.18.4
• Redis Server Version: Redis server v=6.2.6 sha=00000000:0 malloc=libc bits=64 build=c6f3693d1aced7d9
• Node Redis Version: 4.0.1
• Platform: Mac OS 12.0

Error log-

TypeError: Cannot read property 'toString' of null
at Function._RedisCommandsQueue_emitPubSubMessage (/Users/mani/Documents/fanclash/server/node_modules/@node-redis/client/dist/lib/client/commands-queue.js:228:35)
at JavascriptRedisParser.returnReply (/Users/mani/Documents/fanclash/server/node_modules/@node-redis/client/dist/lib/client/commands-queue.js:43:123)
at JavascriptRedisParser.execute (/Users/mani/Documents/fanclash/server/node_modules/redis-parser/lib/parser.js:544:14)
at RedisCommandsQueue.parseResponse (/Users/mani/Documents/fanclash/server/node_modules/@node-redis/client/dist/lib/client/commands-queue.js:196:71)
at RedisSocket. (/Users/mani/Documents/fanclash/server/node_modules/@node-redis/client/dist/lib/client/index.js:330:83)
at RedisSocket.emit (events.js:315:20)
at RedisSocket.EventEmitter.emit (domain.js:483:12)
at Socket. (/Users/mani/Documents/fanclash/server/node_modules/@node-redis/client/dist/lib/client/socket.js:183:44)
at Socket.emit (events.js:315:20)
at Socket.EventEmitter.emit (domain.js:483:12)
at addChunk (_stream_readable.js:295:12)
at readableAddChunk (_stream_readable.js:271:9)
at Socket.Readable.push (_stream_readable.js:212:10)
at TCP.onStreamRead (internal/stream_base_commons.js:186:23)